[tlbuild] xetex bugfix

[Jonathan Kew]

With humble apologies to all those who have built binaries for TL'09  
already, I have just committed a minor xetex bugfix (v.0.994.2) to the  
TeX Live source tree (svn rev. 13951).

If some people are not able to rebuild to pick up this fix, it's not  
critical -- the patch addresses a performance problem but should not  
have any effect on compatibility or features; it does not even  
require .fmt files to be recreated. So if some architectures end up  
getting the fix, and others don't, that's OK -- it will just mean that  
certain (unusual) font-loading usage patterns don't perform as well on  
the unfixed architectures.

BTW, note that if you have an existing build tree around, it should  
work to do "svn update", then cd into Work/texk/web2c and issue "make  
xetex && strip xetex" to get a new binary without repeating the entire  
Build process.

JK